Easy-opening can end having vent means



Nov. 11, 1969 E. c. FRAZE 3,477,608

EASY-OPENING CAN END HAVING VENT MEANS Filed Nov. 21, 1968 5 Sheets-Sheet 1 Nov.-11, 1969 E. c. FRA-ZE 3,477,608

' EASY-OPENING cm END HAVING VENT MEAN'S' Filed Nov. 21, 1968 5 Sheets-Sheet 2 'rwra/ C Praia at, 06x

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NOV. 11, 19 69 1 c, FRAZE 3,477,608

EASE-OPENING CAN END HAVING VENT MEANS Filed Nov. 21, 1968 5 Sheets-Sheet 3 Nov. 11, 1969 E. c. FRAZE 3,477,608

EASY-OPENING CAN END HAVING VENT MEANS Filed Nov. 21, 1968 5 Sheets-Sheet 4 m/ra/vrae, 'rmw/ of F'w e Nov. 11, 1969 E. c. FRAZE EASY-OPENING CAN END HAVING VENT MEANS Filed Nov. 21, 1968 5 Sheets-Sheet 5 Affa'A/M'Djf United States Patent Of 3,477,608 EASY-OPENING CAN END HAVING VENT MEANS Ermal C. Fraze, 355 W. Stroop Road, Dayton, Ohio 45429 Continuation-impart of application Ser. No. 644,957,

June 9, 1967. This application Nov. 21, 1968, Ser. No. 777,584

Int. Cl. B65d 17/24, 51/16; B21d 51/40 US. Cl. 220-54 26 Claims ABSTRACT OF THE DISCLOSURE This disclosure describes an easy-opening container wall having a first line of weakness defining a panel removable from the can end and a tab connected to the panel for causing removal of the panel from the container wall. The tab is connected to the panel by first and second attachment means and a second rupturable line of weakness in the container wall extends between one of the attachment means and the lifting end of the tab. In one form of the invention, the second line of weakness extends between the two attachment means and one of the attachment means is rupturable so that upon lifting of the tab, the rupturable attachment means and the second rupturable line of weakness both rupture to provide vent openings. According to another form of the invention, the second line of weakness extends intermediate the second attachment means and the lifting end of the tab and both of the attachment means are nonrupturable in ordinary usage of the tab. The disclosure also describes a rupturable vent rivet and a method of making same.

BACKGROUND OF THE INVENTION This application is a continuation-in-part of application Ser. No. 644,957, filed June 9, 1967, now abandoned.

Easy-opening containers of the full panel pull-out type usually include a container wall having a panel score line therein defining a panel covering a major portion of such container wall and removable therefrom. The tab is connected to the removable panel by a rivet or other suitable means and the nose end of the tab lies closely adjacent the score line so that uponlifting of the handle or rearward end of the tab, the nose end of the tab bears forcibly on the container wall to initiate severance. of the panel from the container wall. Following such initial severance the user pulls outwardly on the tab to completely remove the panel by a tearing action. Tabs of this type are commonly referred to as front opening tabs.

Containers embodying front opening tabs and/or full panel pullouts are often used on products for which it is necessary or desirable to provide a vent opening prior to the rupture of the line of score which defines the removable panel. Such products may be either packed under pressure, in which event the vent opening is needed to appropriately relieve such pressure, or under vacuum, in which event a vent opening is needed to avoid problems of implosion. As used herein, the expression vent opening has reference to an opening established for the purpose of substantial pressure equalization and is applicable whether it permits entry of air into the container or the exiting of gases therefrom. For example, various types of nutsare vacuum packed in easy-opening containers of the full panel pullout type. When no vent opening is provided, the tab and panel are not infrequently rapidly drawn or pulled into the container by the differential pressure upon initial severance of the panel from the container wall.

Vent openings have been used with easy-opening container walls having rear opening tabs. In one such con- 3,477,608 Patented Nov. 11, 1969 struction a complicated jointed tab construction is connected to first and second rivets. The regions of the can end surrounding these rivets are weakened to form a vent opening and a pouring opening, respectively. By lifting the tab, the user can sequentially remove the two scored regions. This arrangement is not suitable for use with full panel pull-outs or with front opening tabs. Furthermore, the jointed tab construction is relatively complicated and the requirement for scoring two individual areas of the can end further complicate the construction.

Another difficulty with vent openings of this type is that for applications of this type, they are not large enough to fully or adequately equalize the pressure on the inside and outside surface of the can end prior to initiating severance of the panel from the container wall. Thus, for some applications involving a relatively high differential pressure, the vent opening must be of substantial size in order to adequately equalize the pressure prior to initiating severance of the panel from the container wall. If adequate pressure equalization is not achieved, implosion or explosion may occur. Enlarging the size of the vent opening is not any easy task because the can end is made correspondingly more difficult to open.

In order to win customer approval, the easy-opening can end must have a tab which is easily manipulated to open the container. It is important, therefore, that the formation of a vent opening not offer undue resistance to manipulation of the tab. To this end it is desirable to prevent the tab from pivoting about the rivet which connects the same to the panel as such pivoting results in moving the nose end of the tab away from its normal position in which it lies contiguous or closely adjacent the score line. With the nose end of the tab moved away from the line of score, the can end offers substantial resistance to lifting of the tab and failure of the tab by tearing or bending is likely to occur.

SUMMARY OF THE INVENTION The present invention provides for venting of easyopening containers of the type having a large removable panel or utilizing a front opening tab. The venting function is obtained without a material increase in the difficulty of lifting the tab. The present invention also provides a method of making a vent rivet which is adapted to be easily removable from the container wall to form a vent opening. In addition, the present invention provides for firmly anchoring the tab against pivotal .movement which would move the nose end of the tab away from the line of score.

The present invention teaches that a vent opening can be formed in an easy-opening container wall by forming a vent rivet integrally with the container wall and attaching the vent rivet to the tab. More particularly, the tab may be anchored to a removable panel by an anchor rivet so that the tab overlies the rivet with the nose end thereof closely adjacent the score line. The vent rivet may be provided intermediate the rearward or handle end of the tab and the anchor rivet.

The present invention teaches weakly joining the the vent rivet to the removable panel so that upon moving of the rearward end of the tab away from the panel, the vent rivet will be easily severed from the panel to form a vent opening. This eliminates the need for a special scoring step to Weaken the rivet or the sheet material of the panel adjacent the rivet. According to the -teachings of this invention, the weakness of thevent-rivet-to-panel juncture is contributed to by four separate factors. First it is preferred to maintain the outside diameter of the rivet as small as possible, preferably not greater than about This maintains at a minimum the length of sheet material that must be ruptured in removal of the. rivet. Secondly, the sheet material which joins the rivet to the panel should be maintained at a minimum thickness and preferably have a thickness less than the thicknesses of the adjacent portions of the panel or of the vent rivet wall. Third, the exterior surface of the sheet material at the juncture of the vent rivet and the panel should be formed with a relatively sharp corner in radial cross section. Fourth, the metal at the juncture is work hardening to the extent that removal of the rivet is facilitated.

Another way of providing venting of the container is through the use of a line of weakness or vent score line arranged so that as to rupture in response to movement of the rearward end of the tab away from the can end. This type of vent score line is described in application Ser. No. 632,630, Patent No. 3,404,801, which illustrates a vent score line formed partially around an attachment rivet. With the present invention, however, the tab is secured to the tear strip by two rivets spaced longitudinally along the tab with the rearwardmost or innermost rivet being relatively small in plan. The vent score line extends part of the way around the rearwardmost rivet and then generally toward the nose end of the tab. Upon lifting of the rearward end of the tab, the vent score line is ruptured to form a relatively large opening in the can end which can perform a substantial venting function.

The extent to which venting of a container will occur depends upon the size of the vent opening and the time available during which venting can occur. The venting action 'must reduce the pressure differential to an acceptable level prior to the instant at which the severance of the removable panel has begun through fracturing of the score line. Thus, the critical time period for venting purposes is the time from the moment the vent opening is formed until the score line defining the panel is ruptured. As the tab is normally moved away from the can end in a single motion, the present invention teaches that it is desirable to form the vent opening when the tab forms a relatively small angle with the can end to thereby require the user to pivot the tab through a substantial number of degrees following formation of the vent opening in order to initiate severance of the panel.

An advantage of this double rivet construction is that the vent score line is ruptured relatively quickly, i.e. with the tab elevated at only a small angle above the can end. This means that the tab must be raised substantially from the position at which the vent score line first ruptures before the severance of the panel from the can end is initiated. Thus, there is a relatively long period of time between formation of the vent opening and the initiation of severance of the panel, and during this relatively long period of time, pressure equalization is occurring through the vent opening. By way of contrast, when the vent opening is formed only slightly before the instant at which severance of the panel is initiated, there is only a relatively small period of time during equalization of pressure through the vent opening occurrence.

To obtain maximum venting for can ends having a maximum pressure differential thereacross, the present invention teaches the use of a combination of a vent rivet or rupturable attachment means and a vent score line. In this event, the vent score line preferably extends between the vent rivet and the anchor rivet. Preferably, this construction results in fracture of the vent rivet upon a first increment of movement of the tab, fracture of the vent score line to form the vent opening upon a second increment of motion of the tab and ultimately rupture of the score line defining the panel upon the third increment of movement of the tab. In a container having 26 to 29 inches of mercury vacuum, the vent rivet can be sized to drop the pressure differential to about inches of mercury, and the opening formed by the vent score line causes substantial pressure equalization across the can end prior to the time that severance of the panel from the can end has begun.

The vent score line preferably passes closely adjacent and partially around one of the rivets to thereby facilitate 4 rupture thereof. In addition, the vent score line preferably extends laterally of the tab and terminates in end portions lying laterally of the tab. These end portions are preferably curved away from the nearest portions of the score line defining the panel to prevent tearing out of the sheet metal intermediate the vent score line and the panel score line.

Another feature of this invention is that a vent rivet which is weakly joined to the panel as described above can be formed in a simple one step process. More particularly, such a vent rivet may be formed by squeezing a circumscribing zone of the panel between two dies to cause some of the material thereof to flow radially inwardly of the circumscribing-zone to form a hollow rivet. One of the dies has a coining face surrounding a recess and a relatively sharp corner at the intersection of the coining face and the recess. The sharp corner of the die is very important in that it assures that the exterior surface of the sheet material at the juncture of the vent rivet and the panel will be similarly formed with a relatively sharp corner and further helps to assure that the juncture will have a minimum thickness. Thus, this simple one step coining operation forms the desired vent rivet.

The vent rivet is attached to the tab. Preferably, the tab has a countersunk portion with an aperture therein through which the vent rivet projects. The vent rivet is then staked to form a head engageable with the countersunk portion to firmly join the vent rivet to the tab. It is important that the weakened region not be materially thickened or strengthened during the staking operation. Furthermore, metal flow from the rivet through the Weakened region into the circumscribing zone should be held to a minimum so that a maximum amount of metal will be available for bead formation. This can be accomplished by inserting a short staking punch into the rivet during the staking operation. The staking punch should engage or be closely adjacent the weakened juncture so that the thin weakened juncture will form, in effect, a dam for preventing flow of metal therethrough.

Another feature of this invention is that the tab is firmly held against pivotal movement about an axis perpendicular to the panel. This function is obtained by use of the vent rivet which provides a second connection or attachment between the tab and panel. As the tab is connected to the panel at two spaced areas, no pivotal movement which would move the nose end of the tab away from the score line can occur. Accordingly, failure of the tab is less likely.

It is, of course, desirable that the panel of any easyopening container be as easily removed from the container as possible. In order to do this, the nose end of the tab is often formed with a relatively sharp rupturing point. One diffioulty with this arrangement is that when the tab is lifted, the deflection of the tab and of the can end and the pivotal movement of the tab very quickly bring blunt regions of the nose end of the tab into forceful contact with the can end. This means that the point is no longer effective to concentrate stress on the can end adjacent the score line.

The present invention eliminates this problem by tapering the lower edge of the nose end of the tab upwardly as it extends away from the rupturing point. Such upward tapering of the nose end of the tab is sufficient. so that normal deflection of the can end of the tab and pivotal movement of the tab are insufficient to cause any substantially forceful bearing of a broad area of the nose end of the tab against the can end. Thus, the rupturing point is continuously effective to apply a concentrated rupturing force to the can end along the score line.

The invention, both as to its organization and method of operation together with further features and advantages thereof may best be understood by reference to the following description taken in connection with the accompanying illustrative drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of an easy-opening can end constructed in accordance with the teachings of this invention.

FIG. 2 is an enlarged fragmentary plan view of the tab and the adjacent portions of the container wall.

FIG. 3 is a front elevational view of the tab removed from the can end.

FIG. 4 is a fragmentary bottom view of the front portion of the tab.

FIG. 5 is an enlarged fragmentary sectional view taken along line 5--5 of FIG. 1.

, FIG. 5a is a view similar to FIG 5 with the tab manipulated to form a vent opening in the can end and to initiate severance of the panel from the can end.

FIG. 6 is an enlarged fragmentary sectional view showing the dies used to form the vent rivet.

FIG. 7 is a view similar to FIG. 6 with the dies advanced to form the vent rivet.

FIG. 8 is an enlarged fragmentary sectional view showing the staking of the vent rivet.

FIG. 9 is a fragmentary top plan view of an easyopening can end incorporating a vent rivet and a vent score line.

FIG. 10 is an enlarged elevational view of the nose end of the tab shown in FIG. 9.

- FIG. 11 is an enlarged fragmentary sectional view taken along line 1111 of FIG. 9.

FIGS. 12-14 are sectional views similar to FIG. ,11 illustrating the operation of the easy-open can end.

FIG. 15 is a bottom plan view of the tab shown in FIGS. 9 and 10.

FIG. 16 is a fragmentary top plan view of another embodiment of the present invention embodying a vent score line and two attachment rivets.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings and in particular to FIG. 1 thereof, reference numeral 11 designates an easy-opening container wall constructed in accordance with the teachings of this invention. The container wall 11 is a circular can end constructed from sheet material such as aluminum and attached to a container body 13 (FIG. 3) by a peripheral attaching flange 15. The container wall 11 has a line of weakness or score line 17 therein which may be of circular configuration and defines a panel 19 which is removable from the container wall 11. In the embodiment illustrated, the panel 19 is circular and covers a major portion of the container wall 11. A ring tab 21 is attached to the panel by an anchoring rivet 23 and by a vent rivet 25. The anchoring rivet preferably has a larger diameter than the vent rivet 25. j I As seen most clearly in FIG. 2, the tab 21 has a nose end 27, a lifting or handle end 29 and an attachment portion 31. The nose end 27 lies contiguous or closely adjacent the score line 17 and the entire tab 21 extends generally radially of the panel 21. The two spaced separate areas of connection between the tab 21 and the panel 19 make pivotal movement of the tab about the rivet 23 impossible, and accordingly, the position of the nose 27 relative to the score line 17 is not subject to change.

With reference to FIGS. 25, it can be seen that the tab 21 is constructed of sheet metal which is curled along the longitudinal edges thereof to form a continuous outer reinforcing bead 33 which extends completely around the tab exceptfor an interruption at the nose end of the tab shown in FIG. 5. An inner reinforcing bead 35 (FIG. 3) defines an opening 37 (FIG. 2) in the tab 21. A section 39 of the sheet metal is turned downwardly at the nose end 27 intermediate the ends 40 of the reinforcing bead 33. The section 39 projects slightly (e.g. less .010 inch beneath the bead 33 as shown in FIG. 4.

The attachment portion 31 is recessed or countersunk into engagement with the panel 19 as shown in FIG. 3.

The attachment portion 31 has a bottom wall 41 with an aperture 43 therein through which the anchoring rivet 23 projects. The tab 21 is at least substantially longitudinally rigid throughout the full length thereof.

The tab 21 has a second countersunk portion 45 having an aperture 47 through the bottom wall thereof through which the vent rivet 25 projects. The vent rivet 25 is formed integrally with the panel 19 and is joined thereto by an annular weakened region 49. Although various locations for the vent rivet 25 are possible, it is preferred to locate the vent rivet radially inwardly of the anchoring rivet 23.

In the first phase of operation of the present invention, the user grasps the handle end 29 of the tab and lifts it upwardly away from the panel 19. This tends to pivot the tab upwardly; however, such pivoting is resisted by the vent rivet 26 and perhaps slightly by the container wall 11 acting through the nose end 27 of the tab 21. As the upward lifting force reaches a predetermined amount, the weakened region 49 at the juncture of the rivet 25' and the panel 19 ultimately ruptures to form a vent opening 51 (FIG. 5a) and to allow further upward movement of the handle portion 29. It should be noted that substantial lever action is applied to the vent rivet 25 and that the weakened region 49 is sufliciently weak to allow formation of the vent opening 51 with an application of a minimum upward lifting force.

Hereafter, the tab 21 functions as a conventional front opening tab. That is, upon further lifting of the handle end 29, the nose end 27 ultimately initiates rupture of the panel 19 from the container wall 11 to form an opening 53 (FIG. 5a). However, as the vent opening 51 has already equalized or substantially equalized the fluid pressure on opposite sides of the panel 19, none of the adverse effects caused by container pressurization or depressurization will occur.

In the next phase of operation, the tab 21 is pulled outwardly away from the container body 13 to cause continued rupture of the score line 17. Of course, the vent rivet 25 may be used in other types of can ends and in other environments where it is desired to form an opening in one member upon the application of a force which tends to separate such member from a second member.

FIGS. 6-8 illustrate a preferred method of making the vent rivet 25. FIG. 6 illustrates upper and lower coacting dies 55 and 57 which are utilized to form a hollow unstaked rivet 59 (FIG. 7). The lower die 57 has a planar working face 61 on which the container wall 63 is supported. The container Wall 63 is constructed of a flat section of sheet material suchas aluminum and may have a thickness, for example, of .0146".

The upper die 55 has an annular coining face 65 protruding downwardly toward the container wall 63. The coining face 65 surrounds a cylindrical cavity or recess 67. The recess 67 is defined by a cylindrical wall 69 which intersects the coining face 65 to form a relatively sharp corner 71 in radial cross section. For example, the radius on the corner 71 may be about .005 as opposed to a radius of the order of .020" which may be used on a corresponding die for use in making an attachment rivet.

By moving the dies 55 and 57 toward each other as shown in FIG. 7, the unstaked rivet 59 is formed. More particularly, the die 55 may be moved downwardly to cause the coining face 61 to engage a circumscribing zone of the container wall 63 and as downward movement of the die 55 continues, the coining face 65 is operative to cause at least some of the material of the circumscribing zone to flow radially inwardly into the recess 67 to form the rivet 59. This results in thinning of the circumscribing zone to form a thinned coined region 73 which extends completely around the rivet 59.

As shown in FIG. 7, the rivet 59 has a transverse end Wall 75 and a peripheral wall 77 which joins the rivet to the coined region 73. The peripheral wall77 terminates at its lower end in an annular weakened region 79 which joins the rivet to the coined region 73. The peripheral Wall 77 is preferably of minimum thickness at the weakened region 79, e.g. .004" to .005" and increase in thickness as it extends upwardly therefrom.

The relatively sharp corner 71 on the die 55 is operative to form a corresponding sharp corner 81 on the exterior surface of the rivet 59 at the weakened region 79. The sharp corner 71 also assists in causing the weakened region 79 to be of minimum thickness.

The aperture 47 extending through the countersunk portion 45 is placed over the rivet as shown in FIG. 8. Simultaneously, the rivet 23 may be inserted through the aperture 43 in the attachment portion 31 and then staked according to conventional practice. In staking the rivet 59, the tab is clamped between coacting members 85 and 87 and a punch 89 is utilized to strike the transverse end wall 75 to collapse the same and form a bead 91 as shown in FIG. 8. A staking punch 93 extends only a short distance upwardly into the hollow rivet 59 and cooperates with the rim of the aperture 47 to prevent any substantial thickening of the weakened region 79 or any substantial flow of metal radially outwardly during the staking operation. The vent rivet and the rivet 23 may be staked simultaneously, if desired.

It is the presence of the relatively sharp corner 71 that causes the rivet 59 to function as a vent rivet rather than as an attachment rivet which is useful in permanently joining two members together. In addition, with the method described herein, it is important that the weakened region 79 is not materially strengthened or thickened during the staking operation illustrated in FIG. 8.

Thus, the vent rivet described herein can be simply produced in a one step coining operation. The rivet formed by this method may have a very small outside diameter which may be of the order of A The height of the rivet 59 will depend upon the diameter of the coined region 73 and the depth to which the sheet material is coined. That is, the height of the rivet depends upon the volume of the metal displaced in the coining opera tion. Solely by way of example, by coining sheet aluminum of .0246" thickness to leave a residual of .0085" with a coining face having a diameter of .285", a rivet having a A outside diameter and .071 height may be produced.

The weakened region 79 although relatively easily removable from the can end by manipulation of the tab 21, will not rupture due to the ordinary pressure differential on the opposite sides of the container wall. The weakness of the region 79 is brought about by the minimum thickness of such region, the relatively sharp notch or corner 81, and the small diameter of the rivet.

FIGS. 9-15 illustrate an embodiment of the invention utilizing a vent score line and a rupturable vent rivet. FIG. 9 illustrates an easy-opening can end 101 including a can end 103 of sheet material having a peripheral attachment flange 105 for attaching the can end to a can body 107 (FIG. 11). A rupturable panel scoreline 109 is formed in the can end 103 closely adjacent the peripheral flange 105 and defines a removable panel 111. Although various configurations may be utilized, in the embodiment illustrated, the can end 103 is generally circular in plan and the panel score line 109 is also circular and concentric with the can end 103.

A tab 113 of sheet material is attached to the panel 111 by an attachment rivet 115 and by a rupturable vent rivet 117 in a manner similar to that described above in connection with the tab 21. The rivets 115 and 117 may be identical to the rivets 23 and 25, respectively. The tab 113 has .a lifting or handle end 119 and a forward or nose end 121. The tab is mounted on the panel 111 with the nose end 121 thereof substantially overlying a region of the panel score line 109 and with the tab projecting radially inwardly therefrom. The two rivets 115 and 117 prevent the tab from turning about an axis perpendicular to the plane of the can end 103 and the rivet 117 also prevents the lifting end 119 of the tab 113 from projecting substantially upwardly out of the plane of the can end.

A rupturable vent score line 123 is formed in the panel 111 and extends between the rivets and 117. The vent score line 123 has an arcuate central section 125 (FIGS. 9 and 11) which lies closely adjacent the base of the attachment rivet 115 and which extends for about 180 around the rivet 115. The vent score line 123 also has a pair of laterally extending portions 127 and arcuate end portions 129. The lateral portions 127 interconnect the central portion 125 and the end portions 129. As shown in FIG. 9, the vent score line 123 extends laterally beyond the lateral edges of tab 113 and the end portions 129 curve away from the adjacent regions of the panel score line 109 to prevent tearing of the sheet metal lying intermediate the vent score line and the panel score line.

The arcuate portion 125 is the first portion of the vent score line 123 to rupture when the tab 113 is raised. The vent score line 123 is relatively long and this provides a relatively large vent opening in the can end 103. In addition, a relatively long vent score line helps to prevent unintended tearing of the sheet material between the score lines 109 and 123.

Although various kinds of longitudinally rigid tabs may be utilized, FIGS. 9-11 and 15 illustrate a preferred form of tab. The tab 113 is constructed of sheet material such as sheet aluminum and is entirely longitudinally rigid. A peripheral region of the sheet material of the tab 113 is curled inwardly to form an outer reinforcing bead 131 (FIG. 15). Except for regions 133 which permit the fabrication of the tab 113 in a strip of sheet material, the bead 131 extends continuously along the tab periphery and is also interrupted at the nose end 121. The tab 113 has an aperture 135 therein and the sheet material along the rim of the aperture 135 is turned outwardly to form an inner reinforcing bead 137. The tab 113 has a pair of downwardly formed ribs 139 therein lying adjacent the regions 133 to strengthen the tab at the regions Where it would otherwise be'weakened as a result of the discontinuity in the outer bead 131.

The tab 113 has a bathtub section which includes a downwardly sloping wall 141 and a bottom wall 143. The bottom wall 143 has a relatively small diameter aperture 145 for receiving the vent rivet 117 and a larger diameter aperture 147 for receiving the attachment rivet 115.

The outer bead 131 blends into a downwardly directed flange 149 at the nose end 121. The flange 149 has a lower edge 150 which forms a central downwardly projecting point 151. The flange 149 tapers upwardly as it extends laterally outwardly away from the point 151 as best shown in FIG. 10. As the flange 149 extends laterally, it eventually meets end portions 153 of the bead 141; however, the end portions are rolled up quite tight so that the lowermost surface of the nose end 121 continues to extend upwardly as it extends-away from the point 151. Ultimately, the bead regions 153 widen and blend into the remainder of the outer bead 131 as shown in FIG. 15.

With this construction the point 151 projects below the bottom wall 143 and forms the lowermost region of the tab 113. The lower edge of the nose end 121 of the tab 113 extends upwardly to an elevation above thebottorn wall 143.

The operation of this embodiment of the invention is shown in FIGS. 1214. Upon lifting of the handle end 119 of the tab 113 the tab applies an upward force to the rupturable vent rivet 117 sufiicient to rupture same as described hereinabove in connection with vent rivet 25 to form a vent aperture 155. This occurs when the tab forms a relatively low angle with the plane of the panel 111. As soon as the vent aperture 155 is formed, gas can flow therethrough to begin equalizing pressure on opposite sides of the panel 111.

The portions 127 of the vent score line 123 define hinge line about which the tab 113 can pivot during manipulation thereof. As a practical matter, however, due to normal expected deflection of the tab 113 and the can end 103, pivoting may not occur exactly about this line during opening, of the can end.

As the user continues the upward lifting of the handle end 1190f the tab 113, the bottom wall 143 applies an upward lifting force via the attachment rivet 115 to the arcuate region 125 of the vent score line 123. When the tab 113 is still forming a relatively low angle with the panel 111, this force is suflicient to rupture the vent score line 123 and form a vent opening 157 as shown in FIG. 13. Thus, the tab 113 first removes the rupturable vent rivet 117 and then ruptures the vent score line 123 in front opening fashion. At this point, depending upon the dimensioning of the parts of the can end, the point 151 may be bearing against the material of the can end 103 along the panel score line 109 and applying a force thereto.

As upward movement of the lifting end 119 of the tab 113 continues, the vent score line 123 ruptures along the lateral portions 127 to thereby increase the size of the vent opening 157 to permit further equalization of pressure on opposite sides of the panel 111. The vent aperture 155 and the vent opening 157 are partially covered by the tab 113 and to this extent the tab acts as a bafiie to prevent any particles of the product within the can body 107 from being sprayed by the pressure differential from the can body.

Ultimately, the point 151 bears against the material of the can end 103 along the panel score line 109 with sufficient force to rupture the same.'However, the rupturing of the panel score line 109 does not occur until the pressure on both sides of the panel 111 is substantially equal. The initial rupture of the panel score line 109 is shown in FIG. 14 and thereafter, the panel 111 is removed in conventional fashion by exerting an outward pulling force on the tab 113.

The relatively sharp point 151 of the tab 113 projects downwardly and forms the lowest portion of the tab. The lower surface of the nose end 121 of the tab 113 tapers upwardly as it extends away from the point 151. As the tab is raised and the sheet metal components of the easy openingcan end 101 deflects slightly, the point 151 will continue to be substantially the only region of the nose end 121 which is in forcible bearing contact with the can end along the score line 109. Other regions of the flange 149 which would ordinarily forcibly contact the can end 103 during pivotal movement of the tab 113 do not do so because of the taper on the lower edge 150. Similarly, the end portions 153 will not substantially forcibly contact the can end 103. This means that the force supplied to the tab 113 will be concentrated by the point 151 and rupture of the can end along the score line 109 is made correspondingly easier.

FIG. 16 illustrates another embodiment of the inventionwhich is quite similar to the embodiment shown in FIG. 9 and accordingly, corresponding portions of the embodiment of FIG. 16 are designated by corresponding reference characters followed by the letter a. FIG. 16 illustrates an easy-opening can end 101a including a can end 1031: and a tab 113a which are identical to the corresponding portions of the embodiment of FIG. 9 except as specifically noted herein. Thus, the can end 103a has a panel score line 109a which defines a panel 111a to which the tab 113a is rigidly affixed by an attachment rivet 115a and a smaller attachment rivet 171. The attachment rivet 171 corresponds to the vent rivet 117 except that the former is constructed so as not to be rupturable in ordinary usage thereof.

A vent score line 173 is provided in the panel 111a. The vent score line 173 extends between the attachment rivet 171 and the lifting end 119a of the tab 113a. The vent score line 173 has an arcuate region 174 which extends around at least one half of the rivet 171 and two reverse bend portions 175 of which extends arcuately generally toward an adjacent region of the panel score line 109a. The reverse bend portions extend toward the nose end 121a of the tab until they lie along a line which extends transversely of the tab and through the center of the rivet at which location the portions of the vent score line curve away from the adjacent regions of the panel score line 109a.

With this construction, the region 174 of the vent score line 173 will be ruptured when the tab 113a is lifted to form only a small angle with the panel 111a. This is so because the region 174 of the vent score line is moved radially inwardly to the inner side of the rivet 171. The rivet 171 is preferably small in diameter and of smaller diameter than the rivet 115 to permit concentration of forces on the region 174 of the vent score line as the tab 113a is lifted.

Following rupture of the vent score line 173 along the region 174 thereof, further lifting of the tab 113a will rupture the vent score line along the portions 175 to increase the size of the vent opening. The reverse bend portions 175 also serve to prevent tearing out of the sheet metal intermediate the vent score line 173 and the panel score line 109a. Thus, the embodiment of 'FIG. 16 provides a vent opening which is formed in the early stages of lifting of the handle end 119a and which progressively increases in area to a relatively large maximum size as the lifting end is further moved away from the panel 111a.. The tab 113a accomplishes removel of the panel 111a in the same manner described above in connection With FIGS. 12-14.

Although exemplary embodiments of the invention have been shown and described, many changes, modifications, and substitutions may be made by one having ordinary skill in the art without necessarily departing from the spirit and scope of this invention.

I claim:

1. In an easy-opening container wall, the combination of:

acontainer wall of sheet material;

a line of weakness in said container wall defining a tear portion at least partially removable therefrom to define an opening in said container wall;

a. tab constructed of sheet material and having an attachment portion and an at least substantially longitudinally rigid lever portion, said lever portion having a rearward handle end, a forward end and an aperture immediate said attachment portion and said rearward handle end;

means for attaching said tab at said attachment portion thereof to said tear portion so that the tear portion can be removed by manipulaion of said tab;

a hollow vent rivet formed integrally with said containerwall and extending through said aperture in said tab to attach the tab to the container wall, said rivet having a peripheral wall extending outwardly from the container Wall and integrally joined to a contiguous surrounding region of the container wall; and

the sheet material at the juncture of said peripheral wall of said rivet and the surrounding region of the container wall being weakened sufficiently to rupture in response to the application of a minimum outward force on said rearward handle end of said tab to thereby cause separation of said rivet from said surrounding region to provide a vent opening in said container wall whereby further movement of said rearward handle end of said tab away from said panel causes said tab to rupture said container wall along the line of weakness to initiate severance of said tear portion from said container wall.

2. A combination as defined in claim 1, wherein the thickness of the sheet material at said juncture is less than the thickness of said surrounding region.

3. A combination as defined in claim 2, wherein said 75 hollow rivet has an outside diameter of no more than 1 1 about A inch and the exterior surface of the sheet material at said junction is relatively sharp in radial cross section.

4. In an easy-opening container wall, the combination of:

a container wall of sheet material;

a first rupturable line of weakness in said container wall defining a panel at least partially removable from the container wall;

a tab having a nose end and a lifting end;

first attachment means for attaching said tab intermediate said ends thereof to said panel with said nose end of said tab lying closely adjacent said first line of weakness;

second attachment means for attaching the tab to said panel at a location on said tab intermediate said first attachment means and said lifting end of said tab; and

a second rupturable line of weakness in said panel, said second rupturable line of weakness extending between at least one of said attachment means and said lifting end of said tab, said second rupturable line of weakness lying closely adjacent said one of said attachment means and being rupturable in response to movement of said lifting end of said tab away from said container wall to provide a vent opening in said container wall whereby further lifting of said lifting end of said tab causes said nose end thereof to bear on a region of said container wall with sufiicient force to rupture said first line of weakness to initiate severance of said panel from said container wall.

5. A combination as defined in claim 4 wherein both of said attachment means are nonrupturable in ordinary usage of the easy-opening container wall and said second line of weakness extends between said second attachment means and said lifting end of said tab.

6. A combination as defined in claim 5 wherein said second line of weakness extends between said second attachment means and said lifting end of said tab, said second line of Weakness extending at least 180 around said second attachment means and then generally toward said nose end of said tab, said second line of weakness terminating in end portions spaced from said first line of weakness.

7. A combination as defined in claim 4 wherein said second line of weakness extends at least a portion of the distance around said one attachment means and has end portions which extend generally away from the nearest regions of said first line of weakness.

8. A combination as defined in claim 4 wherein said second line of weakness extends at least a portion of the distance around said one attachment means and then extends generally laterally of said tab and terminates in end portions located laterally outwardly from the tab.

9. A combination as defined in claim 4 wherein said line of weakness extends between said first and second attachment means and said second attachment means is rupturable in response to movement of said lifting end of said tab away from the container wall to form a vent aperture in said panel.

10. A combination as defined in claim 4 wherein said tab is constructed of sheet material, an outer peripheral region of sheet material of said tab being bent inwardly to define a reinforcing bead which extends from a first location closely adjacent the nose end of the tab around the lifting end of the tab to terminate at a second location closely adjacent the nose end of the tab and spaced from said first location, the sheet material intermediate said locations being deformed downwardly to form a flange with the lower edge of said flange progressing generally downwardly from said location to define a rupturing point intermediate said locations and overlying said region of said container wall whereby said rupturing point is moved into engagement with the container wall upon lifting of said lifting end of the tab while the portions of said lower edge of said flange lying outwardly of said point do not contact the container wall upon initial lifting of the lifting end of the tab so that said point can apply a concentrated force to the container wall.

11. In an easy-opening container wall, the combination of:

a container wall of sheet material;

a first rupturable line of weakness in said container wall defining a panel at least partially removable from the container wall;

a tab having a nose end and a lifting end;

anchor means for attaching said tab intermediate said ends thereof to said panel with said nose end lying closelyadjacent said first line of weakness;

rupturable attachment means for attaching the tab to said panel at a location on said tab intermediate said anchor means and said lifting end of said tab, said rupturable attachment means being rupturable upon movement of said liftingend of said tab away from said container wall to provide a vent aperture in the container wall; and

a second rupturable line of weakness in said panel extending between said anchor means and said rupturable attachment means, said second rupturable line of weakness being rupturable in response to movement of said lifting end of said tab away from said container wall to provide a vent opening in said container wall whereby further movement of said lifting end of said tab away from said container wall causes said nose end thereof to bear on said container wall with sufficient force to rupture said first line of weakness to thereby initiate severance of said panel from said container wall.

12. A combination as defined in claim 11 wherein the second line of weakness extends at least a portion of the way around said anchor means and terminates in end portions which curve away from the nearest portions of said first line of weakness.

13. A combination as defined in claim 11 wherein said tab has an aperture therein at said location;

said rupturable attachment means includes a hollow vent rivet formed integrally with said container Wall and extending through said aperture in said tab, said rivet having a peripheral wall extending outwardly from the container wall and integrally joined to a continuous surrounding region of the container wall; and

the sheet material at the juncture of said peripheral wall of said rivet and the surrounding region of the container wall being weakened sufficiently to rupture in response to the application of a minimum force to said lifting end of said tab to thereby cause separation of said rivet from said surrounding region to provide the vent aperture in said container wall.

14. A combination as defined in claim 11 wherein upon movement of the lifting end of the tab away from the container wall the rupturable attachment means, the second line of weakness and the first line of weakness rupture in sequence.

15. A tab of the type attachable to an easy-opening container Wall comprising:

a lifting end and a nose end, said tab being constructed of sheet material;

an outer peripheral region of the sheet material of said tab being bent inwardly to define a reinforcing bead which extends from a first location closely adjacent the nose end of the tab around the lifting end of the tab to terminate at a second location closely adjacent the nose end of the tab and spaced from the first location; I Y

the sheet material intermediate said locations being deformed downwardly to form a flange with the lower edge of said flange progressing generally downwardly 13 from said locations to define a centrally positioned rupturing point intermediate said locations;

said tab having a lower wall adjacent the nose end of the tab with an aperture therein for assisting'in attaching the tab to an easy-opening container wall; and a said point lying below said lower wall when the tab is installed on the easy opening container wall.

16. A tab as defined in claim 15 wherein said locations lie above said lower wall when the tab is installed on the easy-opening container wall.

17. A tab as defined in claim 15 wherein the regions of said head immediately adjacent said locations are turned upwardly so that the lowermost surface thereof are no lower than said locations.

18. An easy opening container wall comprising:

a container wall of sheet material;

a line of weakness in said container wall defining a panel at least partially removable therefrom to provide an opening in said container wall;

a tab having a force applying end and a lifting end;

attachment means for attaching said tab to said panel with said force applying end being adjacent said line of weakness;

said panel having a weakened zone defining a segment of said panel removable therefrom to define a vent opening in said panel, at least a portion of said segment being adjacent said tab; and

means for attaching said segment to said tab whereby movement of said lifting end of said tab away from the container wall removes said segment to provide said vent opening and causes said force applying end to initiate severance of said line of weakness.

19. An easy opening container wall as defined in claim 18 wherein said last mentioned means includes a rivet for attaching said removable segment to said tab, said rivet forming at least a portion of said removable segment, said attachment means lying intermediate the ends of said tab, said removable segment lying intermediate said attachment means and said lifting end of said tab.

20. An easy opening container wall comprising:

a container wall of sheet material;

a line of weakness in said container wall defining a panel at least partially removable therefrom to provide an opening in said container wall;

a tab having a force applying end and a lifting end;

first attachment means for attaching said tab intermediate the ends thereof to said panel with said force applying end being adjacent said line of weakness;

said panel being weakened to define a segment at least partially removable from said panel to define a vent opening in said panel, at least a portion of said segment lying adjacent said tab; and

second attachment means different from said first attachment means for attaching said tab to said portion of said segment whereby upon movement of said lifting end of said tab away from said container wall said tab applies a force through said second attachment means to initiate severance of said segment from said panel and said force applying end initiates severance of said panel from said container wall.

21. An easy opening container wall as defined in claim 20 wherein said second attachment means lies intermediate said first attachment means and said lifting end of said tab and said panel has a vent score defining said segment. At least a portion of said vent score lying intermediate said second attachment means and said lifting end of said tab.

22. An easy opening container wall comprising:

a container wall of sheet material;

a line of weakness in said container wall defining a panel at least partially removable therefrom to provide an opening in said container wall;

a tab having a force applying end and a lifting end;

attachment means for attaching said tab to said panel with said force applying end being adjacent said line of weakness, said lifting end of said tab being forcibly movable away from the container Wall to cause said force applying end to rupture said line of weakness;

said panel having first and second weakened zones defining, respectively, first and second segments of said panel, each of said segments being at least partially removable from said panel to provide vent openings in said panel; and

means responsive to movement of said lifting end of said tab away from said container wall to rupture said zones prior to the time that the force applying end ruptures said line of weakness whereby the vent openings are provided in said container wall before severance of the panel from the container wall is initiated.

23. A container wall as defined in claim 22 wherein at least a portion of each of said segments is positioned intermediate said attachment means and said lifting end of said tab with said first segment lying between said second segment and said attachment means, and said last mentioned means ruptures said first and second zones in sequence with said first zone being ruptured first.

24. An easy opening container wall as defined in claim 22 wherein at least a portion of each of said segments lies between said attachment means and said lifting end of said tab, said second zone including a line of score in the container wall adjacent the attachment means and extending between the attachment means and the first segment.

25. An easy opening container wall comprising:

a container wall of sheet material;

a line of weakness in said container wall defining a tear portion at least partially removable therefrom to provide an opening in said container wall;

a tab having a lifting end and an end opposite said lifting end;

means for attaching said tab to said container wall so that upon moving of said lifting end of said tab away from the container wall the tab initiates severance of said tear portion from said container wall;

a container wall having first and second weakened zones defining, respectively, first and second segments of said container wall, each of said segments being at least partially removable from said container wall to provide vent openings therein; and

means responsive to movement of said lifting end of said tab away from the container wall to rupture said zones prior to the time that the tab ruptures said line of weakness whereby the vent openings are provided in the container wall prior to the initiation of severance of the tear portion from the container wall.

26. An easy opening container wall comprising:

a container wall of sheet material;

a first line of weakness in said container wall defining a tear portion at least partially removable therefrom to provide an opening in said container wall;

a tab having a lifting end and an end opposite said lifting end;

first attachment means for attaching said tab to said container wall so that upon movement of said lifting end of said tab away from said container wall the tab initiates severance of said tear portion;

second attachment means adjacent said first attachment means for attaching said tab to said container wall, said second attachment means lying intermediate said first attachment means and said lifting end of said tab;

a second line of weakness in said container wall, said second line of weakness having a portion lying closely adjacent said second attachment means and intermediate said second attachment means and said lifting end of said tab, said second line of weakness having leg portions extending from said first mentioned portion thereof generally toward said first attachment means and then outwardly away from said first attachment means whereby upon movement of the lifting end of said ta-b away from the container wall the tab applies a force to said second attachment means to initiate severance of said second line of weakness to form a large vent opening in the container wall and continued movement of said lifting end of said tab causes said tab to initiate severance of said first line of weakness.

References Cited UNITED STATES PATENTS 3,307,737 3/1967 Harvey et a1 220-54 3,366,270 1/1968 Khoury 220-54 5 3,404,801 10/1968 Silver 220-54 3,416,699 12/ 1968 Bozek Q 220-54 3,434,622 3/ 1969 Czeghedy 220-54 10 GEORGE T. HALL, Primary Examiner U.S. C1. X.R. 

